Studying New Iron-Based Superconductors

Superconductors aren’t just for cool levitation demonstrations; a key discovery in this field could disrupt technologies for computing, medical imaging and power transmission lines as we know them today. The CNBC’s unique expertise and scientific tools are enabling Canadian and international researchers to make cutting edge discoveries in this field.
Source: Canadian Neutron Beam Centre (CNBC)
Contact: cnbc@cnl.ca
Image: Magnetically levitating superconductor

Superconductivity is a phenomenon where materials conduct electricity with no loss of energy.

Currently, superconductivity occurs only at very cold temperatures. While conventional superconductors lose their electrical resistance at about -240 °C, so-called “high-temperature superconductors” containing copper exhibit this exotic property at temperatures as “hot” as -108 °C.

High-temperature superconductors based on iron were discovered only four years ago. These new superconductors are being intensely studied around the world not only because we need to understand the cause of their superconductivity, but because they are stronger candidates for commercial applications due to greater mechanical strength and capacity to conduct electricity than the only previously- known, high-temperature superconductors, which are based on copper.

Prof. Wilson’s research team conducted experiments at the CNBC and at Oak Ridge National Laboratory on the parent compound (BaFe2As2) of a new class of superconductors. BaFe2As2 is called the parent compound because it becomes superconducting when holes, electrons or pressure are introduced into the system.

Prof. Stephen Wilson’s research team from Boston College used one of CNBC’s six beamlines to explore the relation between magnetic and structural properties of a crystal of BaFe2As2, and found surprising changes when they compressed the crystal on the beamline using a clamp.

“Our result offers insight into the magnetic and structural phase transitions in iron-based superconductors” said Prof. Wilson. Slightly compressing the crystal caused unexpectedly large effects on both the alignment of the atoms and the magnetic order. The strain allows magnetic domains to exist at higher temperatures, which may indicate a link between magnetism and superconductivity in these materials.

Neutron scattering facilities such as the CNBC are vital to such studies.

“Neutron scattering has been an invaluable experimental tool in studying these exotic superconductors,” Prof. Wilson said. “It enables scientists to simultaneously explore structural and magnetic properties under different physical conditions not possible to be studied by other techniques. Neutron scattering facilities such as the CNBC are vital to such studies.”

Being able to conduct electricity at higher temperatures without losing energy may be a future outcome of fundamental studies on superconductors. One day, you may see savings on your electricity bill because all the electricity is conserved in superconducting power lines between a generating plant and your home. Or, the computer on your desk or in your palm may be much more powerful than today, because the speed of computer processors today is limited by the heat produced from their electrical resistance. Or, medical diagnostics that require the strong magnetic fields produced using superconductors may become more efficient, precise and accessible.